SortedSetpublic interface SortedSet implements Set| A set that further guarantees that its iterator will traverse the set in
ascending element order, sorted according to the natural ordering of
its elements (see Comparable), or by a Comparator provided at sorted set
creation time. Several additional operations are provided to take
advantage of the ordering. (This interface is the set analogue of
SortedMap.)
All elements inserted into an sorted set must implement the Comparable
interface (or be accepted by the specified Comparator). Furthermore, all
such elements must be mutually comparable: e1.compareTo(e2)
(or comparator.compare(e1, e2)) must not throw a
ClassCastException for any elements e1 and e2 in
the sorted set. Attempts to violate this restriction will cause the
offending method or constructor invocation to throw a
ClassCastException.
Note that the ordering maintained by a sorted set (whether or not an
explicit comparator is provided) must be consistent with equals if
the sorted set is to correctly implement the Set interface. (See
the Comparable interface or Comparator interface for a
precise definition of consistent with equals.) This is so because
the Set interface is defined in terms of the equals
operation, but a sorted set performs all element comparisons using its
compareTo (or compare) method, so two elements that are
deemed equal by this method are, from the standpoint of the sorted set,
equal. The behavior of a sorted set is well-defined even if its
ordering is inconsistent with equals; it just fails to obey the general
contract of the Set interface.
All general-purpose sorted set implementation classes should provide four
"standard" constructors: 1) A void (no arguments) constructor, which
creates an empty sorted set sorted according to the natural order of
its elements. 2) A constructor with a single argument of type
Comparator, which creates an empty sorted set sorted according to
the specified comparator. 3) A constructor with a single argument of type
Collection, which creates a new sorted set with the same elements
as its argument, sorted according to the elements' natural ordering. 4) A
constructor with a single argument of type SortedSet, which
creates a new sorted set with the same elements and the same ordering as
the input sorted set. There is no way to enforce this recommendation (as
interfaces cannot contain constructors) but the JDK implementation (the
TreeSet class) complies.
This interface is a member of the
Java Collections Framework. |
| Methods Summary |
|---|
| public java.util.Comparator | comparator()Returns the comparator associated with this sorted set, or
null if it uses its elements' natural ordering.
| | public E | first()Returns the first (lowest) element currently in this sorted set.
| | public java.util.SortedSet | headSet(E toElement)Returns a view of the portion of this sorted set whose elements are
strictly less than toElement. The returned sorted set is
backed by this sorted set, so changes in the returned sorted set are
reflected in this sorted set, and vice-versa. The returned sorted set
supports all optional set operations.
The sorted set returned by this method will throw an
IllegalArgumentException if the user attempts to insert a
element outside the specified range.
Note: this method always returns a view that does not contain its
(high) endpoint. If you need a view that does contain this endpoint,
and the element type allows for calculation of the successor a given
value, merely request a headSet bounded by
successor(highEndpoint). For example, suppose that s
is a sorted set of strings. The following idiom obtains a view
containing all of the strings in s that are less than or equal
to high:
SortedSet head = s.headSet(high+"\0");
| | public E | last()Returns the last (highest) element currently in this sorted set.
| | public java.util.SortedSet | subSet(E fromElement, E toElement)Returns a view of the portion of this sorted set whose elements range
from fromElement, inclusive, to toElement, exclusive.
(If fromElement and toElement are equal, the returned
sorted set is empty.) The returned sorted set is backed by this sorted
set, so changes in the returned sorted set are reflected in this sorted
set, and vice-versa. The returned sorted set supports all optional set
operations that this sorted set supports.
The sorted set returned by this method will throw an
IllegalArgumentException if the user attempts to insert a
element outside the specified range.
Note: this method always returns a half-open range (which
includes its low endpoint but not its high endpoint). If you need a
closed range (which includes both endpoints), and the element
type allows for calculation of the successor a given value, merely
request the subrange from lowEndpoint to
successor(highEndpoint). For example, suppose that s
is a sorted set of strings. The following idiom obtains a view
containing all of the strings in s from low to
high, inclusive:
SortedSet sub = s.subSet(low, high+"\0");
A similar technique can be used to generate an open range (which
contains neither endpoint). The following idiom obtains a view
containing all of the Strings in s from low to
high, exclusive:
SortedSet sub = s.subSet(low+"\0", high);
| | public java.util.SortedSet | tailSet(E fromElement)Returns a view of the portion of this sorted set whose elements are
greater than or equal to fromElement. The returned sorted set
is backed by this sorted set, so changes in the returned sorted set are
reflected in this sorted set, and vice-versa. The returned sorted set
supports all optional set operations.
The sorted set returned by this method will throw an
IllegalArgumentException if the user attempts to insert a
element outside the specified range.
Note: this method always returns a view that contains its (low)
endpoint. If you need a view that does not contain this endpoint, and
the element type allows for calculation of the successor a given value,
merely request a tailSet bounded by successor(lowEndpoint).
For example, suppose that s is a sorted set of strings. The
following idiom obtains a view containing all of the strings in
s that are strictly greater than low:
SortedSet tail = s.tailSet(low+"\0");
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